Intraoral electromuscular stimulating device and method

ABSTRACT

An intraoral electromuscular stimulation device and method to treat a breathing disorder. The stimulation device includes a first electrode, a first support member that maintains the first electrode in a sublingual location posterior to a frenulum and proximate to one of a first molar, a second molar and a third molar of a patient. A second electrode is maintained in a sublingual position posterior relative to the first electrode by a second support member. A further embodiment of the stimulation device includes a sensor that detects a respiratory parameter of a patient and outputs a signal indicative thereof. A control unit receives the signal from the sensor, distinguishes between inspiration and expiration, and initiates an electrical stimulation at a stimulation time prior to onset of inspiration and continues stimulation through a portion of inspiration at a level sufficient to induce muscle contraction without pain.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention pertains to a device and method forproviding non-invasive intraoral electromuscular stimulation to apatient to treat a breathing disorder, such as obstructive sleep apnea,and, in particular, to a device and method wherein electromuscularstimulation is provided to the patient at a time prior to the onset ofinspiration and continues through a major portion of the inspiratoryphase and is applied at a level sufficient to induce muscle contractionwithout pain and/or is provided bilaterally at sublingual locationsposterior to the frenulum in an anterior-to-posterior and/orposterior-to-anterior direction.

[0003] 2. Description of the Related Art

[0004] Obstructive sleep apnea (OSA) is a medical condition in which theupper airway is repeatedly occluded during sleep despite continuedrespiratory effort. Those afflicted with OSA experience sleepfragmentation and complete or nearly complete cessation of ventilationintermittently during sleep with potentially severe degrees ofoxyhemoglobin desaturation. An OSA sufferer typically experiences manyapnea and/or hyponea events throughout the night. During an apnea event,the resulting hypoxia typically progresses until arousal occurs, whichreestablishes airway patency.

[0005] Symptoms of OSA include snoring, choking and/or gasping duringsleep, fragmented sleep, daytime sleepiness, fatigue and poorconcentration. Airway obstruction can lead to a reduction in tidalvolume, oxygen desaturation and progressive increases in respiratoryrate. The long-term effects of OSA may be translated clinically intoextreme daytime sleepiness, cardiac arrhythmias, pulmonary-arteryhypertension, congestive heart failure and/or cognitive dysfunction.Other consequences of OSA include right ventricular dysfunction, carbondioxide retention during wakefulness, as well as during sleep, andcontinuous reduced arterial oxygen tension. Hypersomnolent sleep apneapatients may be at risk for excessive mortality from these factors aswell as by an elevated risk for accidents while driving and/or operatingpotentially dangerous equipment.

[0006] Studies of the mechanism of collapse of the airway suggest thatduring some stages of sleep, there is a general relaxation of themuscles that stabilize the upper airway segment. This general relaxationof the muscles is believed to be a factor contributing to OSA. Morespecifically, it is generally understood that the patency of the airwaydepends on the activity of the pharyngeal dilator muscles. Common sitesof obstruction are behind the tongue and at the level of the softpalate. In a normal state, the muscles of the tongue, the genioglossus,hyoglossus, styloglossus, palatoglossus and the superior, inferior,transverse and vertical linguals, act to protrude or retract the tongue.Posterior fibers of the genioglossus draw the base of the tongue forwardand anteriorly. One or more of these muscles normally contractreflexively during inspiration. However, it is generally understood thatOSA suffers experience a reduction of lingual muscle activity duringsleep as compared to nonapneics, thereby causing a reduction in airwaypatency.

[0007] Several therapeutic remedies exist for treating OSA. The mostinvasive, yet most likely to be successful, is a tracheotomy, whichcreates an airway bypass around the site of obstruction. Other surgicalremedies include removal of deformed, loose or swollen structures ortissues in the upper airway. It is also known to apply positive airpressure at the mouth and/or nose of the patient to “splint” the airway,thereby maintaining an open passage to the lungs. In addition,pharmacological solutions have also been pursued.

[0008] None of these therapies is successful in all cases. Surgicalrelief is invasive, introduces a potential for surgical complicationsand is appropriate in only a small percentage of cases. On the otherhand, the nasal or nasal/oral mask needed to apply a positive airpressure is not tolerated by some OSA patients. Pharmacologicaltherapies have been, in general, less than satisfactory, and sideeffects are frequent.

[0009] It is also been proposed to treat OSA by electrically stimulatingthe musculature of the upper airway to prevent its relaxation and/orinduce contraction, thereby preventing or minimizing subsequent blockageof the airway. There are two methods in which electromuscularstimulation can be applied to a patient; invasively or non-invasively.Invasive electrical stimulation of a muscle involves implanting one ormore electrodes, either permanently or temporarily within the patient.These subcutaneous electrodes are typically located on or near thenerves that control the muscle to be stimulated. In some applications,the electrodes are placed in direct contact with the target muscle.Subcutaneous electrodes positioned adjacent the muscle or on or near thenerve controlling the muscle to be stimulated have the benefit offocusing the electrical energy on the muscle/nerve to be stimulated.

[0010] However, electrical muscle stimulation utilizing implantedelectrodes requires surgical intervention, the permanent presence offoreign materials within the patient's tissue, and, in someapplications, at least one electrical connection protruding from thepatient. Consequently, there is a potential for infection or irritationat the surgical site and at the site where the electrode or electricalconnection protrudes through the surface of the patient. In addition, itis reasonable to expect that some patients may be apprehensive abouthaving a foreign object surgically placed within their body.

[0011] Non-invasive electrical stimulation of the muscles in the upperairway involves placing an electrode in direct contact with a surface ofthe patient and passing a current through the surface tissues adjacentthe electrode. For example, U.S. Pat. No. 5,123,425 to Shannon et al.teaches applying an electrical stimulation to the exterior surface ofthe patient's neck below the chin to induce contraction of the upperairway muscles. In addition, U.S. Pat. No. 5,792,067 to Karell teachesan intraoral device that applies electrical stimulation to the hardpalate, soft palate or pharyngeal area to induce contraction of theupper airway muscles. U.S. Pat. No. 5,190,053 to Meer teaches anintraoral device that applies electrical stimulation to the genioglossusmuscle via electrodes located on the mucosa on the floor of the mouth oneither side of the frenulum, which is the connecting membrane under thetongue that attaches the anterior portion of the tongue to the floor ofthe mouth.

[0012] While each of these non-invasive stimulation techniques claim toachieve some degree of success in opening the airway, it not clear thatthey are successful in a sufficient number of patients to render any oneof these techniques a viable replacement to the other conventionaltreatments discussed above.

[0013] In addition to using either invasive or non-invasive stimulationon a patient, conventional electromuscular stimulation treatmentstypically initiate stimulation in one of two alternative timing methods.In a first timing method, stimulation is applied only when needed tocounteract a detected breathing disorder, for example, at the onset ofan apnea or when snoring is detected. This technique has the advantagesof, for example, conserving energy and minimizing muscle fatigue.However, it is not clear that this stimulation timing method issufficiently successful in breaking an apnea or stopping snoring in asignificant number of OSA sufferers to be suitable for widescale and/orpractical use.

[0014] According to a second timing method, stimulation is providedindependent of the occurrence of a breathing disorder, such as an apnea,snore or other symptoms of respiratory distress. In this second method,stimulation is typically provided during each inhalation phase of apatient's breathing cycle and typically is initiated at the onset ofinspiration. For example, U.S. Pat. Nos. 5,540,732 and 5,522,862 both toTesterman teach an invasive electrical stimulation system in whichstimulation is applied to the patient in response to sensed inspiration.In an alternative method, such as that taught by U.S. Pat. No. 5,158,080to Kallok, stimulation is provided at all times during the patient'sbreathing cycle, i.e., during the entire inspiratory phase and theentire expiratory phase. Although some success has been claimed whenstimulation is provided independent of the occurrence of a breathingdisorder, it not clear that the degree of success of either technique issufficient to warrant the use such a timing technique on a widescalebasis.

[0015] Other investigators, such as R. P. Schnall et al., as indicated,for example, in an article entitled “Dilatory Effects of Upper AirwayMuscle Contraction Induced by Electrical Stimulation in Awake Humans,”published in Volume 75 of the Journal of Applied Physiology in 1995,pages 1950-65, have experimented with various stimulation techniques,including the timing at which stimulation is initiated and thecorresponding placement of the electrodes within the patient. However,as concluded in this article, the stimulation techniques attempted byMr. Schnall et al. were unsuccessful in decreasing the number ofbreathing disorder events occurring in the test patients.

SUMMARY OF THE INVENTION

[0016] Accordingly, it is an object of the present invention to providean intraoral electromuscular stimulation device for treating a breathingdisorder, such as OSA, that overcomes the shortcomings of conventionalmuscle stimulating devices. This object is achieved according to oneembodiment of the present invention by providing an intraoralelectromuscular stimulation device that delivers intraoral electricalstimulation to a patient to reduce or minimize airway closure. In oneembodiment of the present invention, the electromuscular stimulationdevice includes a first electrode and a first support member thatsublingually supports the first electrode in a position posterior to thefrenulum and generally proximate to a first, second or third molar ofthe patient. The stimulation device also includes a second electrode anda second support member that sublingually supports the second electrodein a position posterior relative to the first electrode.

[0017] It is another object of the present invention to provide anelectromuscular stimulating system for treating a breathing disorderthat does not suffer from the disadvantages of conventional systems.This object is achieved by providing an electromuscular stimulatingsystem that includes an intraoral electrode dental appliance and astimulation unit associated therewith. The dental applicant includes afirst electrode and a first support member that supports the firstelectrode in a sublingual position posterior to the frenulum andgenerally proximate to the first, second or third molar of a patient.The dental appliance also includes a second electrode and a secondsupport member that supports the second electrode in a sublingualposition posterior relative to the first electrode. The stimulation unitprovides stimulating energy to a portion of the patient in ananterior-to-posterior or posterior-to-anterior direction via the firstand second electrodes.

[0018] It is yet another embodiment of the present invention to providea method of providing intraoral electromuscular simulation to thepatient that overcomes the shortcomings of conventional electricalstimulation methods. This objects is achieved, according to oneembodiment of the present invention, by providing a method that includesthe steps of: (1) positioning a first electrode in a patient's mouthsuch that the first electrode is sublingually supported in a positionposterior to the frenulum and generally proximate to one of a first,second or third molar, (2) positioning a second electrode in thepatient's mouth such that the second electrode is sublingually supportedin a position posterior relative to the first electrode, and (3)applying an electrical stimulation to a portion of the patient via thefirst electrode and the second electrode so that the stimulating currenttravels in either an anterior-to-posterior or a posterior-to-anteriordirection in the patient.

[0019] It is a still further object of the present invention to providean intraoral electromuscular stimulation device employing a stimulationtechnique that applies stimulation to the patient at an appropriatetime, duration, location and energy level so as to achieve results thatare an improvement over conventional methods. This object is achieved byproviding an intraoral electromuscular stimulation device that includesa first electrode, a second electrode, a first support member thatsublingually supports the first electrode on a first side of thepatient's mouth relative to his or her midline, a second support memberthat sublingually supports the second electrode in a posterior positionrelative to the first electrode on the same side of the patient's mouth,a sensor that detects a respiratory parameter of the patient and outputsa signal indicative thereof, and a control unit operatively coupled tothe sensor, first electrode and second electrode. The control unitreceives the signal from the sensor, distinguishes between inspirationand expiration of a patient based thereon, and initiates an electricalstimulation of the patient in an anterior-to-posterior orposterior-to-anterior direction via the first and the second electrodesat a start time prior to the onset of inspiration. The control unit alsocontinues the stimulation through a portion of the inspiratory phase andprovides the stimulation at a level that is sufficient to induce musclecontraction but is not sufficient to cause the patient pain.

[0020] It is still another embodiment of the present invention toprovide a method of providing intraoral electromuscular simulation thatapplies stimulation to the patient at an appropriate time, duration andenergy level so as to achieve results that are an improvement overconventional methods. This object is achieved, according to oneembodiment of the present invention, by providing a method that includesthe steps of: (1) positioning a first electrode and a second electrodein sublingual positions within a patient's oral cavity on the same sideof the patient's mouth relative to the midline, with the secondelectrode being positioned posterior relative to the first electrode,(2) detecting a respiratory parameter of a patient and providing asignal indicative thereof, wherein the respiratory parameter is anymonitorable physiological condition that can be used to differentiatebetween inspiration and expiration of the patient, and (3) applying anelectrical stimulation to a portion of the patient between the first andsecond electrodes in a posterior-to-anterior direction or ananterior-to-posterior direction. In this embodiment of the presentinvention, initiating application of electrical stimulation occurs at astimulation time prior to onset of inspiration, continues through aportion of the inspiratory phase and is provided at a level that issufficient to induce muscle contraction but not cause the patient pain.

[0021] These and other objects, features and characteristics of thepresent invention, as well as the methods of operation and functions ofthe related elements of structure and the combination of parts andeconomies of manufacture, will become more apparent upon considerationof the following description and the appended claims with reference tothe accompanying drawings, all of which form a part of thisspecification, wherein like reference numerals designate correspondingparts in the various figures. It is to be expressly understood, however,that the drawings are for the purpose of illustration and descriptiononly and are not intended as a definition of the limits of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a plan view of an exemplary embodiment of a dentalappliance used with a first embodiment of the electromuscularstimulating system of the present invention shown positioned relative toa patient's lower teeth;

[0023]FIG. 2 is a side sectional view of a patient illustrating thesites of stimulation for the device illustrated in FIG. 1;

[0024]FIG. 3 is a schematic diagram of an electromuscular stimulatingsystem according to a first embodiment of the present invention;

[0025]FIG. 4A is a waveform illustrating an exemplary train ofstimulation pulses provided to the patient by the electromuscularstimulating system of the present invention and FIG. 4B is an presentlypreferred embodiment for the stimulating pulse;

[0026]FIGS. 5A and 5B are waveforms of an airflow signal and arespiratory effort signal, respectively, illustrating the points for theonset of electrical stimulation according to the principles of thepresent invention, FIG. 5C is a waveform illustrating the EMG activityof the phrenic nerve, and FIG. 5D is a waveform showing the applicationof stimulation energy to the patient according to the principles of thepresent invention;

[0027]FIG. 6 is a schematic diagram of an electromuscular stimulatingsystem according to a second embodiment of the present invention;

[0028]FIG. 7 is a schematic diagram of an electromuscular stimulatingsystem according to a third embodiment of the present invention thatincludes a pressure support device;

[0029]FIG. 8A is a rear perspective view and FIG. 8B is a bottom view ofa dental appliance that provides electromuscular stimulation and oralpositive airway pressure according to the principles of the presentinvention; and

[0030]FIG. 9A is a rear perspective view and FIG. 9B is a side view of adental appliance that provides electromuscular stimulation andmandibular positioning according to the principles of the presentinvention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS OF THEINVENTION

[0031] Referring now to FIGS. 1-3 there is shown therein a firstembodiment of an electromuscular stimulating system 30 of the presentinvention for providing sublingual electromuscular stimulation to apatient to reduce or minimize the occurrence of a breathing disorder,such as OSA. As best illustrated schematically in FIG. 3,electromuscular stimulating system 30 includes a dental appliance 32 onwhich are provided a first group 34 of electrodes 36, 38 and 40 and asecond group 42 of electrodes 44, 46 and 48. During normal use, dentalappliance 32 is located under the patient's tongue so that theelectrodes are in contact with the patient at sublingual locationsgenerally proximate to the sublingual musculature to provide electricalstimulation to the muscles of the upper airway responsible formaintaining the patency of the airway. Electromuscular stimulatingsystem 30 includes a control unit 50 that controls the application ofstimulation pulses to the electrodes, a power supply 52 for running thesystem and for supplying the stimulation energy, and a respirationsensor 54 for detecting a physiological characteristic of the patientindicative to the patient's breathing. The details of each component andits function in electromuscular stimulating system 30 are discussed ingreater detail below.

[0032] In the illustrated embodiment, first and second groups ofelectrodes 34 and 42 are located on a common, unitary support member 56.It is to be understood, however, that the present invention contemplatesproviding each group of electrodes, pairs of electrodes, and/orindividual electrodes on a separate support member. In addition,although first and second groups of electrodes 34 and 42 are illustratedas each having three individual electrodes, it is to be understood thatas few as two electrodes can be provided in each group so long as atleast one pair of (two) electrodes are sublingually located on each sideof the patient's oral cavity, i.e., located on each side of thepatient's midline within the oral cavity. Conversely, first and secondgroups of electrodes 34 and 42 can each include more than the threeelectrodes shown in the figures, depending on the stimulation pattern tobe achieved.

[0033] Support member 56 is sized so as to fit under the patient'stongue proximate to the mandibular, i.e., lower, teeth 58, as generallyshown in FIG. 1. Once properly positioned, the patient's frenulum 60 islocated adjacent curve 62 in support member 56. In addition, eachlateral arm 64 and 66 of support member 56 extends posteriorly into thepatient's oral cavity sublingually with teeth/gum tissues 68 beinglocated on one side of the support member and the tongue/genioglossusmuscle tissue 70, the outline of which is illustrated by the dashed linein FIG. 1, being located on the other. Support member 56 is sized andconfigured and the electrodes disposed thereon are arranged andconfigured such that, once properly positioned, all of the electrodesare sublingually located within the patient in a position posterior tothe frenulum 60 during normal use.

[0034] As mentioned briefly above, the frenulum is a thin membranegenerally located along the centerline of the mouth that connects theunderside of the tongue to the floor of the mouth. In a normal human,the frenulum is on the order of a few fibers thick and rapidly thickensin an anterior-to-posterior direction along the centerline of the mouth.The tissue commonly referred to as the frenulum ceases in ananterior-to-posterior direction at an undefined point where there is nolonger a thin membrane in the lateral direction, i.e., a directionperpendicular to the centerline, of the mouth. The transition from theregion below the tongue corresponding to the patient's frenulum, whichis identified as region A in FIG. 1, to the area of the mouth below thetongue where there is no longer a thin membrane in the lateral directionand, hence, no frenulum, which is identified as region B, generallyoccurs at a first molar 72.

[0035] The present inventors discovered that optimal results fromelectromuscular stimulation are achieved when the stimulating electrodesare sublingually located in a generally posterior position within theoral cavity. Thus, the present invention contemplates locating thestimulating electrodes in region B, which is posterior to region Acorresponding to frenulum 60, so that all of the electrodes areposterior to frenulum 60. The present inventors postulate thatnon-invasive, sublingual stimulation of the patient in a generallyposterior location in the patient's mouth induces contraction orprevents relaxation of a posterior portion of the genioglossus, which isbelieved to be a portion of the genioglossus muscle that significantlyaffects the degree of opening of the airway.

[0036]FIGS. 1 and 2 illustrate an example of the location of electrodes36-40 and 44-48 relative to the anatomical features of the patientaccording to a presently preferred embodiment of the present invention.As shown, the most anterior electrodes 36 and 44 are generally proximateto first molar 72, middle electrodes 38 and 46 are generally proximateto a second molar 74, and the most posterior electrodes 40 and 48 aregenerally proximate to the third molar (wisdom tooth) 76, if present inthe patient. In addition, electrodes 36-40 and 44-48 are located undertongue 78 in a position generally overlying the middle or posteriorportion of genioglossus muscle 80. Although FIGS. 1 and 2 illustrateelectrodes 36-40 and 44-48 as being generally aligned with a tooth inthe patient's mouth, it is to be understood, however, that aligning theelectrodes with the teeth is not necessary. Furthermore, the dentalappliance and associated electrodes can have a variety of configurationsso long as all of the electrodes are sublingually located within thepatient within region B, which is the region posterior to the frenulum60 and that continues in a posterior direction until it is no longerpossible for an electrode located therein to stimulate the genioglossusmuscle. That is, region B encompasses the area under the tongue thatbegins at the termination point of the frenulum and extends in aposterior direction to the esophagus. See FIG. 2.

[0037] The present invention contemplates that the electrodes in eachgroup of electrodes, i.e., the electrodes located on the same side ofthe patient's mouth or on the same lateral arm, are arranged so that atleast one electrode is posterior to another electrode. For example, inFIG. 3, electrode 38 is posterior to electrode 36 and electrode 40 isposterior to electrodes 36 and 38 during normal use. Locating theelectrodes in each group within the patient in these positions relativeto one another is done because the present inventors also discoveredthat optimum stimulation results are achieved if the stimulation currentflow through the patient is in a generally anterior-to-posterior orposterior-to-anterior direction. The present inventors postulate thatthese directions for current flow optimize contraction because thedirection of current flow through the relevant portions of thegenioglossus coincides with the direction of the muscle tissue and/ornerve directions at that location.

[0038] In the embodiment illustrated in FIG. 1, electrodes 36-40 and44-48 are imbedded in the support member 56 on a common surface 84 sothat once support member 56 is inserted under the tongue, electrodes34-38 and 42-46 are in contact with the patient's tissue at the lowerportion of the oral cavity proximate to the sublingual musculature. Inthe illustrated embodiment, for example, surface 84, on which electrodes36-40 and 44-48 are located, corresponds to the inferior surface ofsupport member 56 and is opposite superior surface 82. In thisembodiment, inferior surface 84 generally faces the patient's jaw andsuperior surface 82 generally faces the patient's hard palate when thedental appliance is properly positioned within the patient.

[0039] It is to be understood, however, that the present inventioncontemplates locating the electrodes at other locations within the mouthor at other locations on the support member so long as the electrodesare located sublingually posterior to the frenulum. For example, theelectrodes can be located on a side surface, rather than a top or bottomsurface, of support member 56, so that the electrodes face a base area86 of the tongue, which is the area where the genioglossus transitionsinto the tongue tissue. Also, the surfaces on which the electrodes aredisposed need not be planar. For example, the portions of the surface onwhich the electrodes are disposed can be raised to facilitate contact ofthe electrodes with the patient. Furthermore, the electrodes themselvesneed not be planar, but may be a raise mound of conductive material, forexample. The present invention contemplates providing the electrodes atlocations on the support member and/or having shapes other than thatshown in the figures so long as the goals of the present invention asdiscussed herein are achieved.

[0040] Electrodes 36-40 and 44-48 can be made from a variety ofconductive materials. More specifically, the electrodes can be made fromany electroconductive material suitable for use in the intraoralenvironment, and, preferably, from a material suitable for long term usein such an environment. Each electrode can be made from the same ordifferent materials. Examples, of suitable materials include, but arenot limited to, metal, carbon-impregnated metal or plastic, andelectroconductive rubber or gels.

[0041] Electrodes 36-40 and 44-48 can have a variety of configurationsdepending on the desired stimulation pattern so long as they are capableof exchanging electric current with the tissue contacting the electrode.For example, the electrodes can be strip electrodes having one of avariety of patterns, rather than the spot electrodes shown in thefigures. The shapes of the electrodes in each group can be the same orcan differ from one electrode to the next, and the electrodes in onegroup need not have the same configuration as the electrodes in anothergroup. The electrodes disposed on support member 56 are illustrated bydashed lines in FIG. 1 because they are located on the underside ofsupport member 56 when viewed from the top as shown in FIG. 1.

[0042] Support member 56 includes a mechanism for attaching the supportmember to the patient. In the illustrated embodiment, a pair ofattaching members 88 and 90 are disposed on either side of the supportmember. The present invention contemplates that attaching members 88 and90 are any structure capable of being secured to the patient's lowerteeth or other jaw structure to maintain the electrodes in asubstantially fixed position relative to the lower teeth. In a preferredembodiment of the present invention, however, the electrodes aremoveable in a generally an up and down direction within the patient sothat the electrodes are maintained in contact with the floor of themouth posterior to the frenulum. It is further preferable that there beminimal movement of the electrodes in the anterior-posterior orposterior-anterior direction and in the medial-lateral or lateral-medialdirection so long as the electrodes are maintained in contact with thepatient's tissues. Any configuration for the support members thatprovides these functions are contemplated within the scope of thepresent invention.

[0043] In the embodiment illustrated in FIG. 1, attaching members 88 and90 are wire-like bands that are generally wrapped around at least aportion of single tooth. It is to be understood, however, that the sizeof each attaching member can be made larger to attach to more than onetooth. Attaching members 88 and 90 are made from any suitablebiocompatible material having sufficient strength to attach supportmember to the patient yet moldable to permit a common (non deformed)configuration of the attaching members to be formed to fit a widevariety of patients having a variety of different dental configurations.It should be noted that if more than one support member is provided,each support member should include a mechanism for attaching thatsupport member to the patient.

[0044] It is to be further understood, that the support members need notbe rigidly attached to the teeth. On the contrary, other embodiments ofthe present invention contemplate that the attaching mechanism beflexible enough to permit slight movement of the support member orsupport members. Making the attachment of the support member to theteeth somewhat flexible is believed to increase patient comfort. Inaddition, the present invention contemplates providing a biasingmechanism so that the support member and/or electrodes are urged intocontact with the patient's tissue. An example of a suitable biasingmechanism is to make the arms of attaching members 88 and 90 spring-likeso that the attached support members are urged into contact with thepatient.

[0045] While the attaching members are illustrated in FIG. 1 as being awire or wire-like configuration, it is to be understood that the presentinvention is not limited to such a structure. On the contrary, thepresent invention contemplates that any mechanism for attaching theelectrodes to the patient can be used for the attaching member. Forexample, a molded member, rather than a metal or metal-like strip can beused to secure the support member within the patient. The moldablemember can be a premolded appliance that generally matches the patient'steeth or a customizable mold that can be configured to match the toothpattern of a specific patient. The present invention also contemplatesthat the attaching member can be secured to the upper teeth so long asadditional support members are provided for sublingually locating theelectrodes at the positions discussed above. The present inventionfurther contemplates using a biocompatible adhesive to secure theelectrodes at the appropriate location within the patient, without anyattachment to the teeth.

[0046] In yet another variation, more permanent devices can be used forsecuring the support member within the oral cavity. For example, apatient may be provided with a support stem that is permanently fixed tothe jaw bone or to a nearby existing tooth or tooth root. In thisembodiment, the support member for the electrodes should be providedwith a coupling member suitable for attaching to the stem so that thesupport member can be selectively attached to the relatively permanentmount within the patient's mouth.

[0047] According to one embodiment of the present invention, electricalstimulation is provided to the patient during selected portions of thepatient's breathing cycle independent of the occurrence of a breathingdisorder, such as an apnea, snore or other symptoms of respiratorydistress. This technique requires sensing the patient's breathing anddistinguishing between the inspiratory phase and the expiratory phase ofthe breathing cycle so that electrical stimulation can be applied duringthe desired portion or portions of the breathing cycle. Sensing thepatient's breathing is accomplished by respiration sensor 54. SeeFIG. 1. Respiration sensor 54 is any device suitable to detect therespiration, i.e., breathing, of the patient. For example, respirationsensor 54 can be a thermister or thermocouple device that detectstemperature changes associated with the exchange of gas with thepatient, a plesmography or inductance belt that detects the respiratoryefforts of the patient, or a flow sensor in communication with thepatient's airway that monitors the flow of gas to and/or from thepatient. It is to be understood that this list of exemplary sensingdevice is not comprehensive or exclusive. On the contrary, the presentinvention contemplates using as sensor 54 any sensor device that detectsa physiological condition of the patient suitable for differentiatingbetween the inspiratory and the expiratory phases of the breathing cycleand that can output signals indicative thereof. Other suitable sensingdevices may measure, for example, the patient's EMG activity or may beacoustically based, to provide an indication of the patient'srespiratory state.

[0048] Power supply 52 is any power source suitable to provide power tocontrol unit 50, respiration sensor 54 (if necessary) and the electrodesin dental appliance 32. Examples, of suitable power supplies areconventional AC power and batteries. Preferably, power supply 52 orcontrol unit 50 includes safety features, such as a fuse, surgeprotector, circuit breaker or optical isolation to prevent fluctuationsin the power supply from adversely affecting the electromuscularstimulation system.

[0049] Control unit 50 is any suitable processor that can receive aninput, such as the input from respiration sensor 54, and based thereon,cause an electrical stimulation energy to be provided to the patient viathe electrodes. Furthermore, control unit 50 and/or power supply 52collectively contain the necessary components for providing electricalstimulation energy to the patient. For example, one embodiment of thepresent invention contemplates that control unit 50 includes a pulsegenerator that provides a series of pulses to the electrodes tostimulate the patient, with the pulse generator being powered via powersupply 52. It is to be understood, however, that power supply 52 caninclude all of the necessary components for generating and shaping thepulse waveform, with the control unit providing the necessary componentsfor gating the flow of the pulses from the power supply. In addition,control unit 50 includes circuitry or components for selecting whichelectrodes are to receive the stimulation energy from the power supply.In FIG. 3, the electrodes are connected to the control unit viahardwires 92. The control unit selects which conductors in hardwires 92are to be provided with stimulation energy. For example, one may desireto stimulate across electrodes 36-38 and thereafter across electrodes36-40. The control unit can be programmed to provide such a stimulationpattern by selecting the appropriate conductors to which to provide theelectrical energy and the appropriate timing pattern.

[0050] According to one embodiment of the present invention, controlunit 50 includes manually operable actuating mechanisms, such asbuttons, dials, knobs or switches, for performing functions such asactivating and deactivating the unit, setting the ranges for the outputenergy strength and/or duration, setting threshold values, settingoperating modes, setting pulse frequency and/or duty cycle andconducting diagnostic routines on the electromuscular stimulatingsystem. The present invention also contemplates that a common controlunit can be used in conjunction with a plurality of sensors 54, aplurality of dental appliances 32, and/or a plurality of sensor-dentalappliance combinations. If one control unit is being used in conjunctionwith a plurality of sensors, a plurality of dental appliances, and/or aplurality of sensor-dental appliance combinations, that control unitwould include a plurality of additional input/output interfaces forconnecting the additional sensors, dental appliances, and/orsensor-dental appliance combinations thereto.

[0051] The control unit can also be configured with any appropriateinput/output interface for exchanging data between the control unit andan external source. For example, one or more interfaces can be providedfor accessing, modifying, or downloading data stored in the controlunit. Such data exchange interfaces can include, but are not limited to,an RS-232 port, modem, coaxial, optical fiber, rf, infrared, ultrasonic,or other interfaces that permit data exchange between the control unitand the external device. For example, data can be provided to thecontrol unit using manual input devices, such as knobs, switches,buttons, and/or keypads coupled to or integral with the control unit.Data can also be provided to, modified or extracted from the controlunit using an external computer that communicates with the control unitusing an appropriate interface.

[0052] Control unit 50 and/or dental appliance 32 can further includewarning devices, such as an audio indicator and/or a visual indicator,that inform the user, or a person monitoring the user, of the conditionof the patient and/or electromuscular stimulating system 30. Forexample, an audio or visual warning can be generated if the patient hasstopped breathing for a predetermined period of time, has begun or hasstopped snoring, and/or has removed or inserted the dental appliance. Ofcourse, an appropriate sensor or plurality of sensors for sensing suchconditions must be provided. For example, a galvanic sensor can beprovided on the dental appliance to detect when it is in contact withthe patent.

[0053] As noted above, the present invention also contemplates providingwarning signals indicative of the status of the electromuscularstimulating system. For example, an audio or visual warning signal canbe generated if the dental appliance exceeds a predeterminedtemperature, if the power provided to the control unit, the sensors, orthe dental appliance has been shut off, falls below a predeterminedlevel or exceeds a predetermined level, if the sensors or the electrodesare not working, have become disconnected or fail to communicate withthe control unit, and/or if there is a short in the system.

[0054] In addition to or in place of the relatively simple audio/visualwarning indicators, other warning devices can be provided. For example,control unit 50 can include circuitry for notifying a remotely locatedthird party of the existence of the condition causing the warning,using, for example, signals communicated via telephone lines.Furthermore, the warning signals, as well as other signals indicative ofthe condition of the patient and/or the electromuscular stimulatingsystem that do not constitute a warning, can be provided to a displaydevice, such as a monitor or LED. Such a display system may beparticularly beneficial in a sleep lab setting where a single controlunit is being used to monitor and stimulate a plurality of patientsunder the supervision of a sleep lab technician.

[0055] An example of the stimulation pulses provided to the patient viaelectromuscular stimulating system 30 are shown in FIG. 4A. In theillustrated embodiment, the simulation pulses are a series of bipolarpulses, each pulse having a positive peak 94 and a negative peak 96. Theseries of bipolar pulses are in the form of a pulse train having aperiod D and are provided across any two electrodes in the same group ofelectrodes as a differential signal, so that a stimulating currentpasses through the patient in an anterior-to-posterior orposterior-to-anterior direction. For example, if the stimulation pulseis provided across electrodes 36 and 38 in electrode group 34, thestimulating current passes through the patient between these twoelectrodes. Because of the positioning of the electrodes within the oralcavity as discussed above, these electrodes are in ananterior-to-posterior relation so that the stimulating current flowthrough the patient is in an anterior-to-posterior orposterior-to-anterior direction. It should be understood that thepresent invention contemplates providing the stimulating pulse acrossany two electrodes in the same electrode group, i.e., on the same sideof the patient's oral cavity, such as between electrodes 36-38, 38-40and 36-40, so long as the direction of stimulation is in ananterior-to-posterior or posterior-to-anterior direction.

[0056] The present invention contemplates providing a pulse train thatincludes one or more stimulating pulses. The details of an exemplaryembodiment of a pulse train are discussed below with reference to FIGS.4A and 4B and the details of the stimulation technique according to oneembodiment of the present invention are discussed below with referenceto FIGS. 5A-5D. It is to be understood that the waveforms shown in thesefigures are not to scale. The characteristics of the stimulating pulsesin the pulse train and the number of such pulses providing during astimulation interval D, which is the time period during which musclestimulation is to be achieved and corresponds to the duration of thepulse train, can vary depending on the amount of stimulating energy tobe provided to the patient. For example, the present inventioncontemplates providing a train of stimulating pulses, wherein each pulsein the pulse train has the same general shape, as shown, for example, inFIG. 4B. It is further preferable that the stimulation energy beprovided to the patient using a current controlled stimulation device,as opposed to a voltage controller, because it has been discerned by thepresent inventors that the voltage of the pulse applied to the patienttends to float or vary with the tissue characteristics, and, inparticular, tissue resistivity, of the patient.

[0057] The present invention further contemplates that the features ofthe pulse train and/or the pulses in the pulse train, such as theamplitudes (positive and/or negative) A₁, A₂, A₃, A₄, . . . , A_(n) anddurations T₁, T₂, T₃, . . . , T_(n) of the individual pulses in thepulse train, the duty ratio of the stimulating pulses in the pulsetrain, as well as duration D of the pulse train, can be varied tocontrol the stimulation energy provided to the patient. These variablescan be set by the control unit using any suitable interface and commonlyvary from patient to patient. A presently preferred embodiment of asingle stimulation pulse is illustrated in FIG. 4B. In this embodiment,the stimulation frequency is preferably in the range of 50-90 Hz.

[0058] It should be further noted that the shape of the pulses in thesame pulse train need not be the same. On the contrary, the presentinvention contemplates providing a train of pulses (or a train having asingle pulse) wherein the pulses in the pulse train have different orunique maximum peaks, minimum peaks, durations, shapes, frequencies solong as the function of adequately stimulating the patient to eliminateor reduce the breathing disorder without jeopardizing the health andsafety of the patient are achieved. Of course, pulse shapes other thanthose illustrated in FIGS. 4A, such as a square, sine, or triangle wave,can be used so long as this purpose is achieved.

[0059] For example, FIG. 4B illustrates a presently preferred embodimentof a pulse 97 for use with the electromuscular stimulation system of thepresent invention. Pulse 97 in FIG. 4B has a positive peak value 99 ofapproximately 140 mV and a negative peak value 101 of approximately −82mV. It is to be understood, that these values can vary depending on thestimulation energy to applied to the patient so long as the energy levelis sufficient to induce muscle contraction without causing pain.

[0060] By modifying the pulse shape, frequency and/or amplitude, thestimulation energy provided to the patient can be controlled. Forexample, it may be desirable, at least in some patients, to ramp thestimulation energy to its operating level over period D to minimize thepotential for patient arousal that may result from the sudden onset ofmuscle contraction.

[0061] The details of when stimulation commences and terminatesaccording to the present invention are discussed below with reference toFIGS. 5A-5D. FIG. 5A is a waveform illustrating a flow signal 98 of apatient breathing normally, i.e., without any perceptible breathingdisorder. Typically, flow signal 98 is output by an airflow meter, suchas a pneumatach or thermister device, as discussed above. FIG. 5B is awaveform illustrating a respiratory effort 100 of the patient producingflow signal 98 of FIG. 5A. FIG. 5C is a waveform illustrating the EMGactivity 102 of the phrenic nerve (diaphragm). FIG. 5D illustrates thestimulation pulses provided to the patient according to an exemplaryembodiment of the present invention.

[0062] Conventional stimulation systems that trigger at the onset ofinspiration, time t₁, attempt to synchronize the opening or themaintenance of the patency of the airway with the action of thediaphragm, which is illustrated in FIG. 5C, so that stimulation isprovided as inspiration commences and continues during the inspiratoryperiod Insp. The present invention, on the other hand, applieselectrical stimulation energy 104 to the patient, as shown, for example,in FIG. 5D, prior to the onset of inspiration.

[0063] One reason for providing stimulation before to the start ofinspiration postulated by the present inventors is to counteract thecollapsing forces that act on the upper airway. For example, onceinspiration commences, a negative pressure is developed in the airway.This negative pressure tends to cause the airway to collapse or reducein cross sectional area. It is believed that if stimulation is providedafter the negative pressure has induced collapse, a greater level ofstimulation energy will be needed to overcome the collapsing forces thanif stimulation is provided prior to collapse.

[0064] In addition, the present inventors postulate that in order toprevent airway collapse in the first place, it is preferable to make thecross-sectional area of the airway as large as possible beforeinspiratory flow begins in the airway. It can be appreciated that areduction in the cross-sectional area of the airway increases theresistance to inspiratory flow, which, in turn, increases the negativepressure in the airway that urges the airway to collapse. If stimulationis applied prior to inspiration, the airway is prevented from reducingin cross-sectional area to thereby minimize the resistance to air flow.Minimizing the resistance to airflow improves airflow, thereby reducingnegative pressure that potentially causes the airway to collapse. Forthese reasons, the present invention induces contraction in the muscularassociated with the upper airway before a collapsing force, such as thenegative pressure developed during inspiration, has the opportunity tocause the airway to collapse.

[0065] The present inventors also discovered that in some patients, oncea collapse or reduction in the airway has taken place, it is relativelydifficult to open the airway by inducing contraction in the upper airwaymuscles. Although it is not clear why this is the case, the presentinventors suggest that once collapse has occurred, the amount of tissuemass that must be moved is prohibitively large. Also, the action of therespiratory muscles in attempting to continue respiration may cause avacuum to be created that tends to urge the airway tissues together,thereby making it especially difficult for an electrically inducedcontraction to be effective in opening the airway. Furthermore, themucus-like characteristics of airway may cause a sealing effect, thatalso makes it especially difficult for an electrically inducedcontraction to be effective in opening the airway.

[0066] A preferred embodiment of the present invention providesstimulation to the target muscles at time t₂, which is between 100 msand 200 ms prior to the onset of inspiration. This time period isselected as a balance between (1) the need to commence stimulation at atime sufficiently prior to the onset of inspiration to achieve the abovefunctions while (2) minimizing muscle fatigue as a result of thestimulation. Thus, the present invention contemplates providingelectrical stimulation at a time prior to inspiration that achievesthese functions and is not intended to be limited to the 100 ms-200 mswindow noted above.

[0067] Causing the stimulation energy to be provided prior toinspiration and, preferably, within the 100 ms and 200 ms time frame,can be accomplished in a variety of ways. For example, flow signal 98and/or effort signal 100 can be used to determine when the patient is atan appropriate trigger point in the expiratory phase. In an exemplaryembodiment of the present invention, the control system determines whenflow signal 98 approaches 0 at the end of the expiratory period andcauses the electrical stimulation to commence when a distance x ofairflow signal 98 from zero at the end of the expiratory periodcorresponds to time t₂. A suitable method for determining when flowsignal 98 is at a point corresponding to t₂ includes comparing theinhale volume to the exhale volume and triggering when the exhale volumeis an appropriate percentage of the inhale volume. It is also possibleto compare the inhale time duration to the exhale time duration andtrigger when the exhale time duration is an appropriate percentage ofthe inhale time duration.

[0068] Similarly, another embodiment of the present invention determineswhen time t₂ is reached based on effort signal 100 of FIG. 5B. Forexample, the control system of the present invention can determine,using a variety of techniques, when effort signal 100 is a distance yfrom a point corresponding to time t₁ and cause the electricalstimulation to commence at a time corresponding to time t₂. Suitableexemplary methods for determining when effort signal 100 is at a point ycorresponding to t₂ include trigging when signal 100 reaches a thresholdvalue corresponding to point t₂, trigging a fixed time period after theslope of signal 100 becomes negative or after some other referencepoint, such as a peak, zero crossing or minimum or triggering after afixed duration of the respiratory cycle. The present invention furthercontemplates adjusting the trigger point using a multiplying factor tocontrol the target point or threshold.

[0069] The length of time that stimulation energy is provided to thepatient should be long enough so that the stimulation energy recruits asufficient amount of muscle fiber to cause the targeted muscle tocontract while minimizing muscle fatigue as a result of the stimulation.It is also preferable that the muscle be maintained in a contractedstate during the portion of the inspiratory period where airway collapseis most likely to take place. For example, a presently preferredembodiment of the present invention contemplates continuing to providestimulation during a major portion of the inspiratory phase of thebreathing cycle, i.e., for more than half of the inspiratory periodInsp. This is accomplished, for example, based on the elapse of timefollowing the application of stimulation so that stimulation stops attime t₃, which is at or after a midpoint M of the inspiratory cycle. Itis to be understood, however, that the present invention contemplatestriggering the cessation of stimulation based on the respiratorycharacteristics of the patient, using, for example, flow and/or effortsignal 98 and 100, so long as stimulation is applied to the patient fora period of time that is long enough to maintain airway patency duringthe critical portion of the inspiratory period but not so long thatmuscle fatigue results.

[0070] Furthermore, the present invention provides the stimulationenergy to the patient at a level sufficient to induce musclecontraction, but not sufficient to cause the patient pain. This isaccomplished, for example, by controlling the duty ratio, frequency andamplitude of the stimulation pulses provided by the system during eachstimulation interval 105. The physical characteristics of the patient,such as the ability of the muscles to contract and pain tolerance, whichare patient dependent, are controlling conditions in determining anappropriate stimulation energy to provide to a patient.

[0071] By controlling the onset of stimulation to (1) begin during at atime that satisfies the above functions and (2) continues through atleast a portion of the inspiratory phase, (3) at a level that inducesmuscle contraction but does not cause pain, and (4) in ananterior-to-posterior or posterior-to-anterior direction sublingually inthe patient mouth, the present invention is believed to provide optimalstimulation results. The present invention further contemplates that oneor more of the electrodes need not be disposed posterior to thefrenulum, as discussed above, so long as the above-described four-partstimulation technique is followed.

[0072] The present invention also contemplates stimulating the patientupon detecting the occurrence of a breathing disorder. Stimulation basedon the occurrence of a breathing disorder can be performed in place ofor in addition to the respiration based stimulation method describedabove. Stimulating based on the occurrence of a breathing disorder, whenused in conjunction with above respiration based stimulation timingtechnique, provides a safety feature in that if the patient experiencesan apnea or snoring, even in the presence of the above-describedrespiration based stimulation timing technique, stimulation can beprovided to break or minimize the apnea or snoring. Of course, in orderfor the present invention to perform stimulation based on the occurrenceof a breathing disorder, control unit 50, for example, must beconfigured to detect the breathing disorder, which can be accomplishedusing any suitable paradigm, to initiate the stimulation upon detectingthe breathing disorder, and to cease stimulation once the disorder isreduced below a predetermined threshold or ceases. If necessary,additional sensors, such as microphone or pressure transducer, can beprovided to detect the breathing disorder.

[0073] The present invention further contemplates controlling theapplication, changes in intensity, and cessation of stimulation based onother criteria. For example, the present invention contemplates delayingthe application of stimulation energy to the patient after theelectromuscular stimulation system has been activated, so that thepatient has the opportunity to fall asleep prior to the start of thestimulation therapy. This can be accomplished, for example, by causing atimer to be activated, either manually or automatically upon activationof the stimulation system, and once the time counts out a predeterminedtime interval, initiating the stimulation therapy. This therapy delayfeature can also be based on a conventional clock so that the user canset the therapy to begin at any preselected time during the night.Similarly, the electromuscular stimulation system of the presentinvention can cease application of the stimulation after the passage ofa selectable time period so that stimulation ceases before the patienttypically awakes, thereby preventing the user from being awaken by thestimulation therapy. This delay in turning off the stimulation therapycan be based on a time interval or based on a conventional clock.

[0074] The present invention also contemplates controlling thestimulation energy applied to the patient in a variety of ways tomaximize patient comfort. For example, one embodiment of the presentinvention contemplates incrementally increasing the intensity of thestimulation energy being delivered to the patient following theactuation of the stimulation system. Typically, this incrementalincrease in stimulation energy takes place over a number of minutes toallow the patient time to fall asleep without a significant stimulationenergy being delivered. The incremental increase can be linear or cantake place in discrete steps. Furthermore, this increase can take placein place of or after the delay period discussed above and is analogousto the ramp feature found in conventional pressure support devices,e.g., CPAP, devices.

[0075] Another embodiment of the present invention contemplatesincrementally decreasing the intensity of the stimulation energy beingdelivered to the patient. This decrease can take place in place of orbefore the delay in turning off the stimulation therapy discussed above.The intensity of the stimulation can also be controlled based on thepatient's sleep stages, assuming, of course, that the appropriatesensors and control systems are provided to detect and classify thepatient's sleep stages.

[0076] The present invention further contemplates providing variousmethods for interrupting the stimulation therapy. For example, a pausefunction that stops stimulation therapy can be initiated by manuallyactuating an input device, such as a button, on the control unit or byactuating a remote input device. The stimulation therapy can also beinterrupted automatically, if, for example, a malfunction is detected orif the patient removes the dental device from their mouth. Restart ofthe stimulation therapy can begin automatically, after the elapse of afixed or selectable time period or once the dental device is reinsertedinto the mouth, for example, or by manually actuating the input device,i.e., actuating an input button or a remote control. Restart of thestimulation therapy can begin at the stimulation energy levels existingprior to the pause, at the initial energy level, or at some otherpreselected level. In addition, the stimulation therapy delay functionand/or the incremental intensity variation function can be institutedduring the restart so that the user again has the opportunity to fallasleep in the absence of any stimulation therapy or in the absence ofsignificant stimulation.

[0077] The present invention also contemplates providing a safetyfeature in which a maximum stimulation energy that can be provided tothe patient is set. This can be accomplished via control unit 50. Thisstimulation energy provided to the patient will not exceed the setmaximum regardless of the stimulation energy set by the user on thecontrol unit. It is preferable that the means by which the maximumstimulation energy is set is not readily accessible so that it cannot bealtered inadvertently or tampered with by the user. The use of apassword that must be input in order to alter the maximum setting is anexample of such a security/safety feature.

[0078] In still another embodiment of the present invention, theelectromuscular stimulation system is provided with an automatic turn-onand/or an automatic turn-off feature. This provides the advantages ofsimplifying the operation of the system and conserving power, forexample. Sensors on the dental appliance, such as a temperature sensoror galvanic type sensor can detect when the appliance is inserted intothe patient's mouth. The output of these sensors are used to control theactuation and deactivation of the stimulation system of the applicationand cessation of the stimulation therapy.

[0079] With the growing popularity of managed healthcare, healthcareproviders are becoming more concerned that the patients actually use theprescribed therapy devices. To meet this concern, the present inventionmonitors patient compliance by storing information regarding the use ofthe electromuscular stimulator, such as the amount of time that the unitwas turned on or that the dental appliance was in contact with thepatient and/or the amount of time that stimulation energy was providedto the patient.

[0080] In one embodiment discussed above, stimulation energy is providedonce an apneic event is detected. In another embodiment, stimulationenergy is provided in synchronization with the patient's respiratorycycle. These, features of the present invention provide a relativelyreliable and accurate indication of the actual usage of theelectromuscular stimulator.

[0081] Furthermore, because the electromuscular stimulator is capable ofcommunicating with external devices using a modem, for example, patientcompliance can be remotely monitored by the healthcare provider withlittle or no patient involvement. This same remote patient compliancemonitoring feature also permits the healthcare provider to monitorand/or control the operating status of the stimulator, for example, bycausing the device to run a diagnostic routine and reports the resultsof that routine or change the operating setting of the device.

[0082] One embodiment of the present invention contemplates that eachcomponent of electromuscular stimulation system 30 illustrated in FIG. 3is separate and isolated from the other components. For example, controlunit 50 is provided in a housing that sits at the patient's bedside,power supply 52 is the AC power available from a conventional outlet,respiration sensor 54 is a device externally attached the patient at afirst location, and dental appliance 32 is inserted in the patient'smouth. It is to be understood, however, that each component need not bephysically separated from the other components. On the contrary,depending on the type, the sensor may be provided on the dentalapplication and/or the power supply may be included in the control unit.In another embodiment of the present invention, all of the componentsare provided on the dental appliance and contained in the patient'smouth during normal operation. FIG. 6 illustrates such an embodiment.

[0083] As shown in FIG. 6, dental appliance 106 includes a supportmember 108 that carries control unit 50, power supply 52, respirationsensor 54, and two groups 110 and 112 of electrodes, one group locatedon each lateral arm. Each group of electrodes, unlike the groups ofelectrodes illustrated in the previous figures, contains only twoelectrodes. However, as in the previous embodiment, the electrodes ingroups 110 and 112 are disposed on the support member such that oneelectrode is posterior to the other electrode when the dental applianceis properly inserted in the patient's mouth.

[0084] Other than being miniaturized to fit on or within the supportmember and, hence, in the patient's mouth, control unit 50, power supply52, and respiration sensor 54 are identical to those discussed above. Itis to be understood, however, some of the components or sub-assembliesof one or more components of the electromuscular stimulating system maybe provided at locations other than on or in the dental appliance. Forexample, depending on the type of respiration sensor used, the presentinvention contemplates that the respiration sensor be located atpositions on or in the patient other than within the mouth. Morespecifically, a belt or sensor that measures the displacement of thechest may be provided at or around the patient's thorax andcommunicates, either using wires or wirelessly, with the control unitand/or a receiver provided on the dental appliance. Finally, the dentalappliance of FIG. 6 includes a pair of attaching members 114 and 116 forsecuring the dental appliance within the mouth. The attaching membersillustrated in FIG. 6, unlike the wire-like devices in FIG. 1, aremoldable, relatively rigid flaps that can be customized to match thepatient's teeth.

[0085] The present invention further contemplates that each component inthe electromuscular stimulating system communicates, as shown in FIG. 3or FIG. 6, via hardwires, or, if appropriate, wirelessly. For example,sensor 54 can wirelessly communicate with control unit 50 or with areceiver or transceiver coupled to the control unit. The presentinvention also contemplates, for example, providing the power supply onthe dental appliance and remotely controlling the application ofstimulation energy from the power supply to the electrodes via thecontrol unit, which is not mounted on the dental appliance. Thisembodiment, like that of FIG. 6, is particularly advantageous in thatthere are no wires passing into the patient's mouth.

[0086] In the previous embodiments of the present invention, theelectromuscular stimulating system is the sole means for treating thepatient's breathing disorder. It is to be understood, however, that thepresent invention contemplates using the electromuscular stimulatingsystem in conjunction with other techniques for treating breathingdisorders. For example, FIG. 7. illustrates the use of electromuscularstimulating system 30 with a pressure support system 120 that appliespositive air pressure at the mouth and/or nose of the patient to“splint” the airway. It is believed that the electromuscular stimulationwill reduce the pressures necessary to be provided by the pressuresupport system 120 in order to splint the airway and treat the breathingdisorder. It is well recognized that the pressure needed to be providedto the patient by the pressure support device to treat the breathingdisorder should be kept as low as possible.

[0087] The present invention contemplates that the electromuscularstimulating system 30 of the present invention can be used inconjunction with most, if not all, conventional pressure supportsystems. Such pressure support systems typically include a pressuregenerator 122 that generates a gas flow, a conduit 124 that carries thegas flow to the patient, and a patient interface device 126 thatcommunicates the conduit with the patient's airway. Examples of pressuresupport devices that are used in conventional pressure support systemsinclude a CPAP (continuous positive airway pressure) device, bi-leveldevices, which provide variable levels of pressure support during thepatient's respiratory cycle, such as the Respironics BiPAP® devices,PAV® devices and PPAP devices. Examples of suitable patient interfacedevices include nasal masks, oral appliances, nasal/oral masks, fullface masks, hoods, nasal cannulas, trachea tube, and any other devicethat communications a gas flow with the patient's airway.

[0088] The present invention also contemplates providing theelectromuscular stimulation in addition with other medical treatments.For example, FIGS. 8A and 8B illustrate an intraoral dental appliance130 that provides electromuscular stimulation and oral positive airwaypressure to a patient according to the principles of the presentinvention. Dental appliance 130 includes a mouthpiece 132 that attachesto the patient's teeth. In a preferred embodiment of the presentinvention a superior surface 134 of mouthpiece 132 attaches to the upperteeth and an inferior surface 136 attaches to the lower teeth. Inaddition, surfaces 134 and 136 are preferably moldable or customizableto correspond to the dental pattern of the patient.

[0089] Mouthpiece 132 includes an orifice 138 passing therethrough toprovide a channel for passing a breathing gas, such as air, from anexternal breathing gas source to the airway of the patient. The externalbreathing gas source can be any suitable pressure support device, suchas the pressure support devices discussed above or a pressurizedcontainer of gas. In the illustrated embodiment, a connector 140 iscoupled to one end of the orifice and a flexible tube 142 is coupled tothe other end. Connector 140 provides a connection for attaching dentalappliance 130 to a breathing circuit (not shown). Flexible tube 142 isconfigured so as to overly the patient's tongue when the dentalappliance is properly positioned with the patient's oral cavity.Flexible tube 142 directs the breathing gas provided by the externalsource over the patient's tongue to the airway to, among other things,minimize drying of the tongue and provide the pressurized gas asdirectly as possible to the patient's airway. The present inventioncontemplates that the length, configuration, and materials for connector140 and flexible tube 142 can vary so long as the above objects areachieved.

[0090] Dental appliance 130 also includes a pair of electrode supportstructures 144 coupled to mouthpiece 132 for supporting electrodes 146.The present invention contemplates that support structures 144 can havea variety of configurations so long as the support functions discussedabove are achieved. Namely, electrodes 146 should be moveable in adirection indicated by arrow 148 (perpendicular to surfaces 134 and 136)and not substantially moveable in other directions, i.e., laterally orin a front-to-back direction, so that the electrodes are held againstthe floor of the mouth posterior to the frenulum during use.

[0091] In the illustrated embodiment, each electrode support structure144 includes a substrate 150 attached to mouthpiece 132 via a supportarm 152. Electrodes 144 are disposed on the inferior side of substrate150. It is to be understood, however, that substrate 150 can beeliminated so that the electrodes are attached directly to themouthpiece using one or more support arms. However, substrate 150 isbeneficial in that it serves as an insulator to ensure that electricalstimulation is provided only to those locations where desired. It is tobe understood that the present invention contemplates that substrate 150and support arm 152 can have a variety of configurations or include oneor more components. In addition, the attachment point and means forattaching the various components of the electrode support structure canbe any suitable point or attaching mechanism so long as the functions ofthe support structures are provided.

[0092]FIGS. 9A and 9B another variation in which the electricalstimulation techniques are used in conjunction with breathing disordertreatment. More specifically, FIG. 9A and 9B illustrate an intraoraldental appliance 160 that provides electromuscular stimulation accordingto the principles of the present invention and mandibular positioncontrol.

[0093] The partial or complete, intermittent airway obstruction thatoccurs during sleep in some OSA sufferers is caused or exacerbated byanterior movement of the lower jaw, referred to as the mandible, duringsleep. To prevent mandibular movement that may adversely affect theairway opening, it is known to provide a mandibular positioning dentalappliance to control the position of the jaw. A further embodiment ofthe present invention incorporates the electromuscular stimulationsystem into a mandibular positioning appliance.

[0094]FIGS. 9A and 9B are rear perspective and side views of anexemplary embodiment of a dental appliance 160 that includes themandibular positioning function discussed above and the electromuscularstimulation function according to the principles of the presentinvention. Mandibular positioning dental appliance 160 includes amouthpiece 162 that attaches to the patient's upper and lower teeth.Mouthpiece 162 includes two components, an upper member 164 thatattaches to the patient's upper teeth or bone structure and a lowermember 166 that attaches to the teeth or jaw. More specifically, asuperior surface 168 of upper member 164 attaches to the upper teeth andan inferior surface 170 of lower member 166 attaches to the lower teeth.Surfaces 168 and 170 are preferably moldable or customizable tocorrespond to the dental pattern of the patient so that the upper andlower members securely attach to the patient. An inferior surface 172 ofupper member 164 generally faces a superior surface 174 of lower member196. A mechanical linkage 176 couples upper member 164 and lower member166 to one another and controls or limits the movement of one memberrelative to the other at least in certain directions. In a preferredembodiment of the present invention, at least one spacer 177 is providedat the anterior portion of the mouthpiece and attached to the uppermember or lower member to maintain a comfortable spacing between thesemembers. It is to be understood that one or more spacers can be providedat other locations within the mouthpiece and that the spacer or spacerscan be formed integrally with the mouthpiece member.

[0095] In a preferred embodiment of the present invention, linkage 176,which is preferably provided on both lateral arms of the mouthpiece forstability, permits at least limited movement of lower member 166relative to upper member 164 in a direction indicated arrows 178.However, linkage 176 limits movement of lower member 166 relative toupper member 164 in a direction 180 to a certain predetermined range sothat the patient's jaw, which is attached to lower member 166, does notmove posteriorly relative to the upper member more than a predeterminedamount. The predetermined amount is an amount which, if exceeded, tendsto result in a reduction or blockage of the airway. Thus, the mandibularpositioning feature allows for movement of the lower member relative tothe upper member but permits only limited movement of the lower memberin the direction of arrow 180 relative to the upper member to preventthe patient's jaw from moving posteriorly relative to the upper teeth toa degree that might result in airway collapse or reduction.

[0096] While control of the movement of the lower member relative to theupper member is provided in the illustrated embodiment via a mechanicallinkage, it is to be understood that the present invention is notlimited to this example of a position control mechanism. For example,the present invention contemplates that the upper member and the lowermember can be fixed to one another, as in the embodiment illustrated inFIGS. 8A and 8B, for example. If desired, the upper and lower memberscan be fixed to one another in an offsetting relation to provide adesired mandibular positioning. In these embodiments, an airway, such asorifice 138, can be provided to allow the patient to breath through themouth. Of course, if the patient breaths through the nose, such anorifice is not needed.

[0097] As in the embodiment illustrated in FIGS. 8A and 8B, dentalappliance 160 includes a pair of electrode support structures 144coupled to mouthpiece 162 for supporting electrodes 146. Theconfiguration for the support structures and/or the electrodes, theplacement location of the support structures on the mouthpiece andattachment mechanism, the functions and the support structures andalternative configurations are the same as those discussed above withrespect to FIGS. 8A and 8B. Therefore, detailed descriptions of theseembodiments and modifications are omitted from the present discussion ofFIGS. 9A and 9B for simplicity.

[0098] Although the invention has been described in detail for thepurpose of illustration based on what is currently considered to be themost practical and preferred embodiments, it is to be understood thatsuch detail is solely for that purpose and that the invention is notlimited to the disclosed embodiments, but on the contrary, is intendedto cover modifications and equivalent arrangements that are within thespirit and scope of the appended claims.

What is claimed is:
 1. An intraoral electromuscular stimulation deviceadapted to provide intraoral electrical stimulation to a patient, saiddevice comprising: a first electrode; a first support member adapted tosupport said first electrode in a sublingual location posterior to afrenulum and generally proximate to one of a first molar, a second molarand a third molar of a patient; a second electrode; and a second supportmember adapted to support said second electrode in a sublingual positionposterior relative to said first electrode.
 2. An intraoralelectromuscular stimulation device according to claim 1, wherein saidfirst support member and said second support are fixed to one another todefine a dental appliance.
 3. An intraoral electromuscular stimulationdevice according to claim 2, further comprising at least one attachmentmember operatively connect ed to said dental appliance, said attachmentmember being adapted and arranged to secure said dental appliance to ananatomical structure within a patient's oral cavity.
 4. An intraoralelectromuscular stimulation device according to claim 2, wherein saiddental appliance includes a passageway adapted to communicate an airwayof a patient with a pressure support system for providing a breathinggas to a patient at an elevated pressure.
 5. An intraoralelectromuscular stimulation device according to claim 1, furthercomprising: a third electrode; a third support member adapted to supportsaid third electrode in a sublingual position posterior to a frenulumand generally proximate to one of a first molar, a second molar and athird molar located on a side of a patient's oral cavity opposite saidfirst electrode; a fourth electrode; and a fourth support member adaptedto support said fourth electrode in a sublingual position posteriorrelative to said third electrode.
 6. An intraoral electromuscularstimulation device according to claim 5, wherein said first supportmember, said second support member, said third support member and saidfourth support member are fixed to one another to define a dentalappliance.
 7. An intraoral electromuscular stimulation device accordingto claim 1, further comprising: a third electrode; and a third supportmember adapted to support said third electrode in a sublingual positionposterior relative to said second electrode.
 8. An intraoralelectromuscular stimulation device adapted to provide intraoralelectrical stimulation to a patient, said device comprising: a firstelectrode; a second electrode; and supporting means for supporting saidfirst electrode and said second electrode such that said first electrodeis sublingually supported at a position posterior to a frenulum andgenerally proximate to one of a first molar, a second molar and a thirdmolar of a patient and said second electrode is sublingually supportedin a position posterior relative to said first electrode.
 9. Anintraoral electromuscular stimulation device according to claim 8,wherein said supporting means is a unitary dental appliance on whichsaid first electrode and said second electrode are disposed.
 10. Anintraoral electromuscular stimulation device according to claim 9,wherein said dental appliance includes a passageway adapted tocommunicate an airway of a patient with a pressure support system forproviding a breathing gas to a patient at an elevated pressure.
 11. Anintraoral electromuscular stimulation device according to claim 8,further comprising attaching means for securing said supporting means toan anatomical structure within a patient's oral cavity.
 12. An intraoralelectromuscular stimulation device according to claim 8, furthercomprising: a third electrode, wherein said supporting means supportssaid third electrode in a sublingual position posterior to a frenulumand generally proximate to one of a first molar, a second molar and athird molar on a side of an oral cavity opposite said first electrode;and a fourth electrode, wherein said supporting means supports saidfourth electrode in a sublingual position posterior relative to saidthird electrode.
 13. An intraoral electromuscular stimulation deviceaccording to claim 8, further comprising a third electrode, wherein saidsupporting means also supports said third electrode such that said thirdelectrode is sublingually supported at a position posterior to saidsecond electrode.
 14. An electromuscular stimulating system comprising;(1) an intraoral electrode dental appliance, comprising: a firstelectrode, a first support member adapted to support said firstelectrode in a sublingual position posterior to a frenulum and generallyproximate to one of a first molar, a second molar and a third molar of apatient, a second electrode, and a second support member adapted tosupport said second electrode in a sublingual position posteriorrelative to said first electrode; and (2) a stimulation unit operativelycoupled to said first electrode and said second electrode, saidstimulation unit providing stimulating energy to a portion of a patientvia said first and said second electrodes such that stimulation of saidportion of said patient takes place in one of an anterior-to-posteriordirection and a posterior-to-anterior direction.
 15. An electromuscularstimulating system according to claim 14, wherein said stimulation unitincludes: a power supply; and a control unit operatively coupled to saidpower supply to provide stimulating energy to said first and said secondelectrodes as a series of pulses and to control at least onecharacteristic of said series of pulses.
 16. An electromuscularstimulating system according to claim 14, wherein said stimulation unitfurther includes a sensor adapted to detect a physiologicalcharacteristic of a patient and to provide a signal to said stimulationunit indicative of said physiological condition, and wherein saidstimulation unit controls said series of pulses based on said signalfrom said sensor.
 17. An electromuscular stimulating system according toclaim 14, further comprising: a third electrode; a third support memberadapted to support said third electrode in a sublingual positionposterior to a frenulum and generally proximate to one of a first molar,a second molar and a third molar located on a side of a patient's oralcavity opposite said first electrode; a fourth electrode; and a fourthsupport member adapted to support said fourth electrode in a sublingualposition posterior relative to said third electrode, wherein said astimulation unit is operatively coupled to said third electrode and saidfourth electrode and provides stimulating energy to a patient via saidthird and said fourth electrodes such that stimulation of said patienttakes place in one of an anterior-to-posterior direction and aposterior-to-anterior direction.
 18. An electromuscular stimulatingsystem according to claim 14, further comprising: a third electrode; anda third support member adapted to support said third electrode in asublingual position posterior relative to said second electrode.
 19. Anelectromuscular stimulating system according to claim 14, wherein saidfirst support member and said second support are fixed to one another todefine a dental appliance and wherein said dental appliance includes apassageway adapted to communicate an airway of a patient with a pressuresupport system for providing a breathing gas to a patient at an elevatedpressure.
 20. An electromuscular stimulating system according to claim14, further comprising a pressure support system providing a gas flow toa patient, said pressure support system comprising: a pressuregenerator, a conduit operatively coupled to said pressure generator, anda patient interface device operatively coupled to said conduit forcommunicating said conduit with an airway of a patient.
 21. Anelectromuscular stimulating system comprising: (1) an intraoralelectrode dental appliance, comprising: a first electrode, a secondelectrode, and supporting means for supporting said first electrode andsaid second electrode such that said first electrode is sublinguallysupported in a position posterior to a frenulum and generally proximateto one of a first molar, a second molar and a third molar in a patientand said second electrode is sublingually supported in a positionposterior relative to said first electrode; and (2) stimulating meansfor providing stimulating energy to a portion of a patient through saidfirst and said second electrodes such that stimulation of said portionof said patient takes place in one of an anterior-to-posterior directionand a posterior-to-anterior direction.
 22. An electromuscularstimulating system according to claim 21, further comprising: a thirdelectrode, wherein said supporting means supports said third electrodein a sublingual position posterior to a frenulum and generally proximateto one of a first molar, a second molar and a third molar on a side of apatient's oral cavity opposite said first electrode; and a fourthelectrode, wherein said supporting means supports said fourth electrodein a sublingual position posterior relative to said third electrode. 23.An electromuscular stimulating system according to claim 21, furthercomprising sensing means for detecting a physiological characteristic ofa patient and for providing a signal to said stimulating meansindicative of said physiological condition, said stimulating meanscontrolling impulses provided to said patient based on said signal fromsaid sensing means.
 24. A method of providing intraoral eletromuscularsimulation comprising: positioning a first electrode in a patient's oralcavity such that said first electrode is sublingually supported in aposition posterior to a frenulum and generally proximate to one of afirst molar, a second molar and a third molar; positioning a secondelectrode in a patient's oral cavity such that said second electrode issublingually supported in a position posterior relative to said firstelectrode; applying an electrical stimulation to a portion of a patientbetween said first electrode and said second electrode.
 25. A methodaccording to claim 24, further comprising: detecting a physiologicalcharacteristic of a patient; and providing a signal indicative of saidphysiological condition, wherein said applying electrical stimulationstep includes controlling electrical pulses provided to a patient basedon said signal indicative of said physiological condition.
 26. A methodaccording to claim 24, further comprising: positioning a third electrodein a patient's mouth such that said third electrode is sublinguallysupported in a position posterior to a frenulum and generally proximateto one of a first molar, a second molar and a third molar on a side of apatient's oral cavity opposite said first electrode; positioning afourth electrode in a patient's oral cavity such that said fourthelectrode is sublingually supported in a position posterior relative tosaid third electrode; applying an electrical stimulation to a portion ofa patient between said third electrode and said fourth electrode.
 27. Amethod according to claim 24, wherein positioning said first electrodeand said second electrode includes sublingually locating a dentalappliance on which said first electrode and said second electrode aredisposed and securing said dental appliance to an anatomical structurewithin a patient's mouth.
 28. A method according to claim 24, furthercomprising a step of providing a flow of gas to a patient via a patientinterface device.
 29. An intraoral electromuscular stimulation deviceadapted to provide intraoral electrical stimulation to a patient, saiddevice comprising: a first electrode; a first support member adapted tosupport said first electrode in a sublingual location within a patienton a first side of a patient's oral cavity relative to a patient'smidline; a second electrode; a second support member adapted to supportsaid second electrode in a sublingual location within a patientposterior relative to said first electrode and on a same side of apatient's oral cavity with respect to a patient's midline; a sensoradapted to detect a respiratory parameter of a patient and to output asignal indicative thereof; and a control unit operatively coupled tosaid sensor, said first electrode and said second electrode, saidcontrol unit receiving said signal from said sensor and distinguishingbetween inspiration and expiration of a patient based thereon, saidcontrol unit initiating an electrical stimulation of a patient in one ofan anterior-to-posterior and posterior-to-anterior direction via saidfirst and said second electrodes at a stimulation start time prior toonset of inspiration, continuing stimulation through a portion ofinspiration, and providing stimulation at an energy level sufficient toinduce contraction of a targeted muscle without inducing pain.
 30. Anintraoral electromuscular stimulation device according to claim 29,wherein said stimulation start time is between 100-200 ms prior to onsetof inspiration
 31. An intraoral electromuscular stimulation deviceaccording to claim 29, wherein said control unit determines a start timefor initiating stimulation by comparing said signal to a thresholdvalue.
 32. An intraoral electromuscular stimulation device according toclaim 29, wherein said sensor is one of a respiratory effort detectorand a device adapted to measure a flow of fluid.
 33. An intraoralelectromuscular stimulation device according to claim 29, wherein saidfirst support member is adapted to support said first electrode in asublingual location posterior to a frenulum and generally proximate toone of a first molar, a second molar and a third molar of a patient, andwherein said second support member is adapted to support said secondelectrode in a sublingual position posterior relative to said firstelectrode.
 34. An intraoral electrode stimulation device according toclaim 33, wherein said first support member and said second support arefixed to one another to define a dental appliance.
 35. An intraoralelectrode stimulation device according to claim 33, further comprising:a third electrode; and a third support member adapted to support saidthird electrode in a sublingual position posterior relative to saidsecond electrode.
 36. An intraoral electrode stimulation deviceaccording to claim 29, further comprising: a third electrode; a thirdsupport member adapted to support said third electrode in a sublingualposition on a side of a patient's oral cavity opposite a side associatedwith said first electrode; a fourth electrode; and a fourth supportmember adapted to support said fourth electrode in a sublingual positionon said side of a patient's oral cavity opposite said side associatedwith said first electrode posterior to said third electrode.
 37. Anintraoral electrode stimulation device according to claim 36, whereinsaid first support member is adapted to support said first electrode ina sublingual location posterior to a frenulum and generally proximate toone of a first molar, a second molar and a third molar of a patient,wherein said second support member is adapted to support said secondelectrode in a sublingual position posterior relative to said firstelectrode, wherein said third support member is adapted to support saidthird electrode in a sublingual location posterior to a frenulum andgenerally proximate to one of a first molar, a second molar and a thirdmolar on a side of an oral cavity opposite said first electrode, whereinsaid fourth support member is adapted to support said fourth electrodein a sublingual position posterior relative to said third electrode, andwherein said control unit provides stimulating energy to a portion of apatient via said third and said fourth electrodes such that stimulationof said portion of said patient takes place in one of ananterior-to-posterior direction and a posterior-to-anterior direction.38. A method of providing intraoral electromuscular simulationcomprising: positioning a first electrode and a second electrode insublingual positions within a patient's oral cavity on a same side ofpatient's oral cavity relative to a patient's midline, wherein saidsecond electrode is located in a position posterior relative to saidfirst electrode; detecting a respiratory parameter of a patient andproviding a signal indicative thereof, said parameter being sufficientto differentiate between inspiration and expiration of a patient; andapplying an electrical stimulation to a portion of a patient betweensaid first electrode and said second electrode in one of aposterior-to-anterior direction and an anterior-to-posterior direction,wherein initiating application of said electrical stimulation occurs ata stimulation start time prior to onset of inspiration and continuesthrough a portion of inspiration, and wherein stimulation is provided atan energy level sufficient to induce contraction of a targeted musclewithout inducing pain.
 39. A method according to claim 38, wherein saidstimulation start time is between 100-200 ms prior to onset ofinspiration
 40. A method according to claim 38, wherein said step ofapplying electrical stimulation includes determining a start time forinitiating stimulation by comparing said signal to a threshold value.41. A method according to claim 38, wherein said respiratory parameteris one of a respiratory effort and a flow of fluid.
 42. A methodaccording to claim 38, wherein positioning said first electrode and saidsecond electrode includes locating a dental appliance on which saidfirst electrode and said second electrode are disposed within an oralcavity of a patient and securing said dental appliance to an anatomicalstructure within a patient's mouth.